Naphthenohydroxamic acid manufacturing process



United States Patent N APHTHEN OHYDROXAMIC AGID MANUFAQ TURING PROCESS Helen-Sellei-Beretvns, Chicago,- 11]., assignor to standard Oil qsam any, Ghieag'o; Ill}, a corporati n of- Indiana No I h'awing. Application July 20 19 6 Serial N0. 599,026.

4 Claims; (6]; 2603500 R 2,818,429 Patented. Dec. 31, 1957 2 rnediatel'y added-with-ra id stirring while maintainingtlie temperature in the -range of 70 to130 andeffecting the addition in a period of about 3 to 30' minutes, theshorter times being desirable at higher temperatures in there s 'cctfivleranges; I then-immediately add about 2 rnolesot NaoH-permoleHENOHHCI withrapid stirring during period of about .lt'o l fi'hours, preferably; about .S 'lEO hour while'maintainingthe reaction m-ixture"-ata'teinper= attire inthc-ran ecf 76th 130 R; preferably-$110100? F; "At least-aho l'ti'pcr'cent of the-NaOHis prefer-holy added'iih dry solid form and the remaining NaOH-rn-ayhe addetf as a concentrated aqueous solution,- it bei ni por tant" that the total; amount of water pfes'e'n't in th re action mixture after"the"addition of" NaOH Be not- 'niore on: a- Weight hasis than theamcunt-of addcd Na-QH hut referably less. Instead of adding s'oIidNaOH, I triay ice ' add all of it in an aqueous solution which is sufiicifi-tly thenohyd'rox'arni'c acid and points out that is 'useful as a rust inliihitor-for turbine-oils, trans'fo'ritier'oil's and-the like. Heretofore the commercial manufacture of-su'ch hydroxamic acid; hasre uiredrolongedreaction time thereby limiting the amount of product obtainahlein iven equipment; an object of this invention-ism rovide an-irnpr ved technique which will' -enable" the-reaction time-t6 he enormously decreased" With consequent" increase iii fll through ut -of-jsu'ch plan-ti While high -yields cr er'nde H naphthcn-ohynroxaniic; acids were oh'tainahlein the'prior thaw discovered" that the quality of'naphthenohyd it:

antic acid can he remarkably enhanced=byempl'cyin a sequence of steps and conditions which will minimize otn p eting reactions. The additionofre'eititeirits s'liould be at relatively high temperatures in the range chari ma 70 to rapid",- e; less than two hoursin--cach -c-"ase (pfe'fefably 3%) to 90r'ninntcs)" but the reactionwhich is mainly enacted after addition of NaOH should be at about 4016' 70 F (preferably .60i F.),fo1: aperiod of about 1 to 20 hours, preferably about '4to' 12*honrs; Thennhount of water which 'iSrPI-BSGIlbin: the systemafter all sodium hydroxide has been added thereto sh'ouldbe on'a weight basis not; mdrethtimthe-amount of sodiu ydroxidogwliich is 'e'fiiplo'yedt"but'preferablylaw-this tcature has hee'n foiliid to be very important. droxylamine salt be added in alcoholic solution rather than as a solid or slurry.

Specifically, I first dissolve the hydroxylamine hydrochloride in about 4 to 10 volumes of methyl alcohol (although ethyl alcohol or isopropyl alcohol may be used) at substantially reflux temperature, i. e. at about 150 F. I then cool the solution to at least about 70 F. and I have found that even though some of the hydroxylamine hydrochloride may come out of solution, this is of no consequence it the methyl ester of naphthnic acid is im- I (preferably 80- 1 10 F.) and shonld be qui te It is also important that the hyis added with" stiriring'at 8010- 1 30 P1,. the 'reaction m'rzo ture is cooled to about 40 to 70 F.,,,preferablyva'botlt 59 ton60 F.; and theireact'ion is allowed to proceed after which said mixture i's' acidified with an=apptopriate acid,. ,like-;sulfurie acid, un'tilit is acid to methyl'iora nge.

The mixtureis then allow'ecl'to stratify, the'upp6t21iaphthenohytlioxamici aci'd layer is separated and either'washed with an aqueous Salt Sdl1iti0ii 01"; dilutedwitlr 2111' equal weight of light oil and-washed with water until neutral to con-go test-paper.- A-fterthewashing s-tep theproduc-tis dried..in.an y, known manner, preferably by adding-anhydrous .zsodium. sulfatesthereto followe'dby ,tiltrationh p The: fihalproductnobtained from naphth'eini'eacid with about ZS OGmOIe'cular weight is. a naphthenohygroxatiiic acid'whichflc'ontainsiabout 3L0to 318 percent nitrog a product of higherpurity thansheretofore roduced and "it is ;therefore.-moreeffective. as a rust inhibitor foftu'rbitie oilsand theJike. As ,a specific example ofithe invention, 28 grams of H NOHlHCI' is dissolved under reflux con} ditions in 1 12 cc.-,of a substantially anhydrous methyl alcohol The-,solutionis cooled toabou't 6Q 9 O El.and 1001'. grams; of. methyl .naphth'enate (250 280! coin "ifiihg weight,calculatedjrornt the sa onifieation number. (of the ester used)" is added theretoiwitl i apid stirringina period of about. 1-5 .min tes while holding the temperature at aboutiloo" Next. a hot solution cont'airiiug' 35 g ains of NaOHand .30 grainsof water is-a'dded with rapid stirring, in aperiodlcf {about /2 ,hour'whil'e holding the tern} peraturetof the mixture in the rangefiof about "to' F.- The..reaction mixture istthen immediatelygc'ooled'to about 50 to 60 F;' andheld, at this t'eniperat'lire" fora periodnof about4 hour's after which reaction perioitlie mixture,is;acidified.with sulfuric acid until acidto methyl orange. Theeacidifiedlmi-xture is allowed to stratify and the-upper-naphthenohydroxamic acid layer is removed from tthetlowe'rklayer, washed'with an aqueoussaltsolution, driecl rby, addifiga-nhydrous sodiumsulfate and tered'. Thetresultin 'roduct is found to have a'nitrogen content 10f 3.5iperj'cerlt .bywe'igjht. When the reaction is carried out with substantially the ame amounts of the same' reactants. -withfllOO Ice. of'.. a. 5 0 ercent ethylal= cohol-water solution oft'h e 28 grams H 'NDHHCI 'and 66 grams of a 50 percent NaOH solution by weight in water (giving 83 parts by weight of water to 33 parts by weight of NaOH) the product contains only 2.3 percent nitrogen by weight.

In another example wherein all of the caustic is introduced in the form of pellets and no water is present but wherein the steps and conditions are otherwise the same as in the foregoing example, a product containing 3.6 weight percent nitrogen is obtained. However, in commercial operations it is difiicult to maintain the reaction mixture at constant temperature if all of the caustic is added in solid form as pellets and the preferred technique is to add about 70 to 90, e. g. 80, percent of the caustic in the form of a saturated or approximately 50 percent solution and then adding the remaining to 30, e. g. 20, percent of the NaOH in solid form.

It will be noted in the above examples that hydroxlyamine hydrochloride was employed in alcoholic solution rather than in solid or slurry form; this has been found to be essential for obtaining most advantageous results. The amounts of reagents will, of course, depend on the combining weight of the naphthenic acid ester which can be calculated from the saponification number of the ester used; each mole of ester requires 1 mole of hydroxylamine hydrochloride and 2 moles of sodium hydroxide. A series of tests were made using a naphthenic acid having an average combining Weight of about 250 employing my improved technique with results shown in the following The low nitrogen content of the product produced in Test A was the result of the excessive amount of water, this test having been included for the purpose of comparison and not as an example of the invention. Other tests have shown that even in the absence of excessive water, the desired results are not obtained unless the defined procedural steps and conditions are adhered to, including the step of initially dissolving H N.OH.HCl in alcohol.

As an example of large scale operation, 870 pounds of methanol were refluxed with 274 pounds of H N.OH.HCl for about 1 hour, then cooled to 90 F. and 980 pounds of methyl naphthenate of 195-220 saponification number were added within 30 minutes at 90-105 F. The mixture was then cooled to about 60 F. and 565 pounds of 48 percent caustic solution was added with stirring in about 70 minutes, during which time the temperature arose to a maximum of about 110 F. and was maintained at an average of 80 to 100 F. Then, 73 pounds of solid NaOH was added within 20 minutes with vigorous stirring while the temperature was held in the range of 88 to 94 F. A sample was drawn 30 minutes after the NaOI-I addition, acidified-and washed free of acid and salt; it had a nitrogen content of 3.0 percent. The rest of the batch was stirred for a total of 12 hours at about 50 to 60 F., then treated with sulfuric acid, blended with 50 percent white oil, washed and dried; the resulting 50 percent product had a nitrogen content of 1.6 to 1.7 (corresponding to a product nitrogen content of 3.2-3.4). and it had excellent rust preventative qualities.

While other esters than the methyl ester of naphthenic acid may be employed as pointed out in the prior patent (2,397,508), I have found that the methyl ester gives best results. The methyl ester may be made from various types of naphthenic acids, these being adequately defined in the prior patent. Since the reaction per se, equivalents of various reactants, and product recovery steps are clearly described in the prior patent, it is unnecessary to discuss them herein.

I claim:

1. In the process of making naphthenohydroxamic acid by reaction of a naphthenic acid ester with a hydroxylamine hydrochloride and sodium hydroxide in an alcoholic solution followed by acidification with sulfuric acid and product purification, the improved method of operation which comprises adding the ester and then the sodium hydroxide to an alcoholic solution of hydroxylamine hydrochloride at temperatures in the range of about to 130 F. with rapid stirring, cooling the reaction mixture, after the addition of sodium hydroxide, to a temperature in the range of 40 to 70 F. and holding the reaction mixture in said temperature range for a period of about 1 to 20 hours, and introducing into said total reaction mixture a total amount of water which is not substantially more on a weight basis than the amount of sodium hydroxide introduced thereto.

2. The method of claim 1 which includes the step of introducing at least a part of the sodium hydroxide in solid form.

3. The method of making naphthenohydroxamic acid which comprises dissolving hydroxylamine hydrochloride in about 4 to 10 volumes of an alcohol having less than 4 carbon atoms per molecule at substantially reflux temperature, cooling the resulting solution to a temperature not higher than about 70 F. and adding about 1 mole of methyl naphthenic acid ester per mole of hydroxylamine hydrochloride to said cooled solution with stirring in a period of about 3 to 30 minutes while holding the temperature of the solution in the range of about 70 to 130 F., then adding about 2 moles by weight of sodium hydroxide per mole of H N.OH.HCl in about .1 to 1.5 hours while maintaining the mixture at temperatures in the range of about 70 to 130 F., the amount of water introduced with the sodium hydroxide being sufficiently small so that the total amount of water in the reaction mixture is not more on a weight basis than the amount of sodium hydroxide therein, cooling the reaction mixture after the sodium hydroxide is added to a temperature in the range of 40 to 70 F. and holding the temperature of the reaction mixture in said range for a period of about 1 to 20 hours, then acidifying the mixture with sulfuric acid until it shows an acid reaction to methyl orange, and recovering a substantially pure naphthenohydroxamic acid from the acidified reaction mixture.

4. The method of claim 3 which includes the step of adding about 70 to percent of the sodium hydroxide in the form of a substantially saturated aqueous solution and thereafter adding the remainder of the sodium hydroxide in substantially dry form.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN THE PROCESS OF MAKING NAPTHENOHYDROXAMIC ACID BY REACTION OF A NAPHTHENIC ACID ESTER WITH A HYDROXYLAMINE HYDROCHLORIDE AND SODIUM HYDROXIDE IN AN ALCOHOLIC SOLUTION FOLLOWED BY ACIDIFICATION WITH SULFURIC ACID AND PRODUCT PURIFICATION, THE IMPROVED METHOD OF OPERATION WHICH COMPRISES ADDING THE ESTER AND THEN THE SODIUM HYDROXIDE TO AN ALCOHOLIC SOLUTION OF HYDROXYLAMINE HYDROCHLORIDE AT TEMPERATURES IN THE RANGE OF ABOUT 70 TO 130*F. WITH RAPID STIRRING, COOLING THE REACTION MIXTURE, AFTER THE ADDITON OF SODIUM HYDROXIDE, TO A TEMPERATURE IN THE RANGE OF 40 TO 70*F. AND HOLDING THE REACTION MIXTURE IN SAID TEMPERATURE RANGE FOR A PERIOD OF ABOUT 1 TO 20 HOURS, AND INTRODUCING INTO SAID TOTAL REACTION MIXTRUE A TOTAL AMOUNT OF WATER WHICH IS NOT SUBSTANTIALLY MORE ON A WEIGHT BASIS THAN THE AMOUNT OF SODIUM HYDROXIDE INTRODUCED THERETO. 